Apparatus for sterilizing



March 31, 1970 MCDONALD ETAL 3,503,703

APPARATUS FOR STERLIZING 3 Sheets-Sheet 1 Filed Dec. 14, 1964 FIG. 2

FIG. 3

INVENTORS ROBERT L. MCDONALD BY ALVIN E BERNREUTHER ATTORNEYS March 31,1970 c o ETAL 3,503,703

APPARATUS FOR STERLIZING Filed Dec. 14, 1964 3 Sheets-Sheet 2 FIG. 4

I NVENTORS ROBERT L. MCDONALD 6 BY ALVIN E BERNREUTHER ATTOR NEYS March31, 1970 Filed Dec. 14, 1964 IT) 5 r 3 FIG. 8

R. L. M DONALD ETAL APPARATUS FOR STERLIZING MANUALLY START OFF 56 on H878 OPEN 5| OPEN 56 OPEN 3 Sheets-Sheet 3 1N VENTORS ROBERT L. MCDONALDALVIN F. BERNREUTHER ATTORNEYS United States Patent 3,503,703 APPARATUSFOR STERILIZING Robert L. McDonald, Rochester, and Alvin F. Bernrenther,Macedon, N.Y., assignors, by mesne assignments, to Sybron Corporation, acorporation of New York Filed Dec. 14, 1964, Ser. No. 417,974 Int. Cl.A61l 3/ 00, 5/00, 7/00 US. Cl. 21-91 5 Claims ABSTRACT OF THE DISCLOSUREA sterilizing apparatus having a gas impermeable barrier, a completelyflexible and collapsible gas impermeable bag having an aperture forreceiving articles to be sterilized and adapted to be mounted ingastight connection with the barrier. Suitable means for connecting thebag onto the barrier in gastight relationship and exhaust means forreducing the internal pressure in the bag and for circulating air in thebag and valving and controls for carrying out a sterilizing cycle in thebag.

This invention relates to improved method and apparatus for sterilizingwith a gaseous sterilant. In the past, it has been common practice inthe sterilizing art to utilize a rigid structure as the sterilizingchamber in which effective sterilization is carried out. This inventionprovides improved method and apparatus for sterilizing with a flexible,collapsible sterilizing chambersuitable for use with gaseous sterilantssuch as ethylene oxide or betapropiolactone.

It is an important object of our invention to provide method andapparatus utilizing a flexible, collapsible sterilizing chamber.

It is a furtherimportant object of our invention to provide improvedmethod and apparatus for introducing, circulating and exhausting the gassterilant from the sterilizing chamber which is particularly well suitedfor sterilization with a flexible, collapsible sterilizing chamber.

According to this method and apparatus, it has been discovered that itis particularly suitable to sterilize at less than atmospheric pressurewith a flexible bag; this guarantees n0 leakage of agent to the areasurrounding the flexible sterilizer chamber in case of damage to the bagitself.

It is a further object of our invention to provide novel i (2) Thisinvention permits portability of large capacity 7 units, sterilizationof rigidly mounted frames, machines and the like, at location. Thisportability eliminates the hazard of moving contaminated materialsthrough noncontaminated areas. g (3) The separable gas impermeablebarrier which provides a mechanical and control section for the flexiblebag permits servicing an unlimited number and variety of sterilizingchambers by a single mechanical and control section.

(4) The arrangement of the gas impermeable barrier "ice or mechanicaland control section automatically and safely controls and disposes ofthe sterilant if a leak should develop in the sterilizing chamber.

(5) As the sterilizing chamber is operated at less than barometricpressure, the flexible sterilizing chamber will collapse to the size ofthe load resulting in a minimum requirement for sterilant.

(6) Forced circulation of the sterilant atmosphere through and aroundthe load insures that the sterilizer load has a maximum exposure to thesterilant in a minimum time, permitting shorter cycles than existing gassterilizers.

(7) Disposal of the sterilant gas and odors by means of chemicalconversion, absorption, or adsorption within the mechanical and controlsection eliminates the requirement for an external vent permittingportability and minimum setup time.

(8) The purging phase of the cycle and aeration with heated sterile aireliminates or greatly reduces odors contained in a sterilizer load. Inthis regard, provision can be made to introduce and circulate throughthe load an aromatic masking or odor destroying material.

It is a general object of this invention to provide method and apparatuswhich fulfills the above enumerated advantages.

It is a further object of our invention to provide an improved methodand apparatus for sterilization which is portable.

It is a further object of our invention to provide a flexible,collapsible sterilizing chamber having an opening adapted to receivegoods to be sterilized which is releasably or separably connected to thebag.

This invention contemplates a gas impermeable barrier to which isconnected a completely flexible, collapsible gas-impermeable bag havingan aperture permitting insertion therein of articles to be sterilizedand preferably mounted horizontally to the barrier.

Other objects and advantages of this invention will be particularly setforth in the claims and will be apparent from the following description,when taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a first embodiment of thisinvention;

FIG. 2 is a top view with parts broken away of the FIG. 1 embodiment ofthis invention;

FIG. 3 is a bottom elevational view of the FIG. 1 embodiment of thisinvention;

FIG. 4 is a schematic view of the FIG. 1 embodiment of this invention;

FIG. 5 is a schematic view of a second embodiment of this invention;

FIG. 6 is a cross-sectional view of a third embodiment of thisinvention;

FIG. 7 is a perspective view of a fourth embodiment of this inventionwith parts broken away;

FIG. 7A is an enlarged partial cross-sectional view of of the circledportion of FIG. 7; p FIG. 7B is a reduced left-end view of the FIG. 7embodiment illustrating the following tray 20C;

FIG. 8 is a schematic wiring diagram of the control circuit suitable foruse with all embodiments of thisine vention; and

FIG. 9 is a timed sequence chart of the automatic cycle controlled bythe circuitry of FIGS.

With reference to the drawings, basically this invention comprises a gasimpermeable barrier generally indicated by the numeral 10, whichincludes a mechanical and control section described more in detailhereinafter, a gas impermeable, completely flexible and collapsible bag12 releasably or separately connected to the barrier 10. The barrier 10includes control means for introducing suit- 3 able sterilant adapted toassume a gaseous state through the barrier into, through and out of thebag 12 thereby to satisfactorily sterilize articles contained in the bag12.

BAG AND CONNECTION TO BARRIER The bag may'be re-usable or disposable,single use type of any thin, flexible membrane, film, or laminant suchas polyethylene, nylon-vinyl or clear polystyrene, Buna N and Buna Srubbers, hycar and nylon fabric of neoprene coated fabric forming acompletely flexible, collapsible gas-impermeable sterilizing chamber inlieu of the conventional rigid type pressure vessel. The sterilant isadapted to assume the form of vapor, gas, aerosol, or other finelydivided particulate matter and it will be understood that as hereinused, the term gaseous, gas or gaseousstate will be construed to broadlydefine such forms of matter.

The flexible bag or sterilizing chamber 10 is releasably secured orconnected in air-tight relationship to the barrier, as for example, byadhesive tapes, clamping devices, airtight, pressure sealing zippers,screw hold-down plates, or any other suitable means. The FIG. 1embodiment illustrates one type releasable connection between theflexible bag or sterilizing chamber 12 and the barrier 10 whichcomprises a set of screw hold-down plates 16, 17 and 18 defining variousrectangular shapes (see FIG. 2) outlining corresponding but smallerholes provided in the lower surface of the bag 12 which are designed tosurround certain inlets, outlets and control apparatus in the barrier10. A clear plastic cover 93 overlies certain control apparatus to sealit from the sterilizing chamber when the center hold-down plate 17 issecured to tray 20.

The three hold-down plates 1618 overlie the edges of the correspondingholes in the flexible bag and are secured by a plurality of hold-downscrews 21 to a wooden tray or bag support 20 to which the barrier 10 isconnected. These hold-down plates 1618 are releasable to enable repairof the barrier 10 and controls included therein. It is also a desirablefeature of this invention to provide means for releasably connecting thebag to the barrier to enable the barrier to be used with a variety offlexible bags.

The FIG. 1 embodiment also includes a pressure sealable zipper 22 whichextends substantially entirely around the periphery of the bag 12 in ahorizontal plane; thereby to substantially release the upper part 21 ofthe bag from substantiallythe entire bottom part 23 and the barrier 10This zipper provides an aperture in the bag adapted to receive the goodsto be sterilized which are illustrated in broken line (five mattresses24 with spacers 25 interposed therebetween to facilitate sterilizationthereof). The upper part 21 only remains attached to the barrier byreason of an unzippered portion extending partially along the left-handside of the bag 12 as viewed in FIGS. 1 and 2 so that the upper part ofthe bag 12 opens back somewhat in the manner of a clam shell. It will beunderstood that the substantially releasable connection such as thezipper 22 could be extended around the entire periphery so that it maybe completely releasable or detachable from the barner.

In the second embodiment illustrated in FIG. 5, there is schematicallyshown another manner in which the flexible bag 12A may be releasably ordetachably connected to the barrier 10A by a pair of releasable clamps26 and 27 respectively mounted at the upper end of an inlet flexiblehose 28 and outlet flexible hose 29 communicating with the flexible bagsterilizing chamber 12A. This would be in lieu of the screw typehold-down plates 16-18 inclusive of FIGS. 1-4. As is shown andillustrated in this drawing, the bag 12A would have an openingZZA as isprovided by the air-tight zipper 22 of the FIG. 1 embodiment adapted forintroducing and withdrawing goods to be sterilized.

In FIG. 6, is illustrated a flexible bag 12B and a gas impermeablebarrier. It will be understood that a conven- 4 ventional stainlesssteel door frame 30 and a conventional annular or rectangular sterilizerdoor 31 with radial locking arms 32. The door 31 in the conventionalmanner is hinged (not shown) to the door frame 30. A conventionalperipheral sealing gasket 33 is provided intermediate the door frame 30and door 31 to provide a gas impermeable barrier. It will be understoodthat a conventional mechanical and control section well known in the artfor controlling the introduction and exhaustion of gas and moisture isincorporated with the FIG. 6 embodiment to complete the gas impermeablebarrier with controls.

The upper right-hand corner of the flexible bag 12B ripherally spacedscrews 40 transversing the frame 30, the and a spring 36 attached to asupporting structure (not shown) for supporting the bag upright. Theflexible bag 12B is releasably connected to the barrier 10B and theframe 30 is likewise releasably connected to a peripheral supportingbase 38 of channel iron by a plurality of peripherally spaced screws 40transversing the frame 30, the bag 12B and base 38, thereby toreleasably connect the flexible bag 12B to the gas impermeable barrier10B. The base 38 is rigidly mounted to an upper supporting structure orwall 39 and to a lower supporting structure or floor 41. At the right,there is provided a channel iron base 43 rigidly mounted to the floor41. There is a laterally extending tray or support 38A rigidly mountedto the bases 38 and '43 for supporting the bag 12B and goods to besterilized therein. The aperture through which the goods are receivedmay or may not be the same aperture which is releasably connected ingas-tight relationship with the gas impermeable barrier.

In the FIG. 7 embodiments, parts corresponding to the FIG. 1 embodimentare identified by the same numeral followed by the suflix C. There is acompletely flexible collapsible bag 12C of plastic or rubberized fabrichaving an opening or aperture 100 adapted to receive the goods to besterilized such as matteresses 24C. Also the aperture 100 is adapted toreceive the periphery of a horizontally disposed lateral tray or support20C rigidly mounted on a base generally indicated by the numeral 38Cwhich extends under the tray 20C. Base 38C includes four conventionalcasters 42C, only the front two of which are illustrated, therebyproviding a portable structure as shown in FIG. 1. However, as shown inFIGS. 7 and 7B, the tray 20C is divided into three sections d, e, and f.Sections d and f are hinged to center section e and fold upwardly asillustrated in broken line in FIG. 7B to pass through doorways.

As shown in FIGS. 7 and 7A, there is a releasable band or clamp 102which defines a U in cross-section and extends around the entireperiphery of the tray 20C. Releasable band 102 may include any type ofconventional releasable latch (not shown) to draw the band 102 tightabout the bag 12C which it overlies in order to seal the bag at theperiphery of the tray 20C in gas-tight relationship With agas-impermeable flexible covering 101 overlying the tray 20C. 7

A gas impermeable barrier 10C rigidly mounted to the base 38C includescontrols section 104 for housing the controls illustrated in FIGS. 1-4and described more in detail hereinafter, communicating with theflexible sterilizing bag 12C through the tray 20C and covering 101 inthe same manner as illustrated in FIGS. 1-4. Thus, covering 101 Wouldcomprise part of the gas impermeable barrier 10C. It will be understoodthat the controls could be of any conventional known type which fulfillsuitable functions for sterilizing within the flexible chamber. In thealternative, the controls mounted in control section 1'04 maycommunicate with the flexible sterilizing chamber directed throughopenings. provided in the bag with a releasable connection therebetween.The ampule C mounted on the outside of the controls section 104 suppliesthe gaseous sterilant. Y

A significant aspect of this invention is to preferably mount theflexible bag 12, 12A, 12B or 12C horizontally, that is, so that itsgreatest length lies in a horizontal plane rather than in a verticalplane. It will be understood as contrasted between, for example, theFIG. 1 and FIG. 6 embodiments, that the gas impermeable barriers 10 and10B respectively, to which the horizontally mounted bag is connected,may lie in either a vertical or horizontal plane depending upon thedesired use of the sterilizer and the type of releasable connection, orfor any other reason. The desirability of mounting the bag horizontallyin length versus vertically in length is obviously to prevent verticaldistribution of weight and bulk of the goods which could, among otherdisadvantages, result in the bag being tipped when hit and inadvertentlydislodged from the barr1er.

DETAILS OF BARRIER 10 This invention includes a novel method andapparatus for introducing, circulating and exhausting air and sterilantthrough the apparatus above described which is particularly suitable fora flexible bag sterilizer. In FIG. 4, we have schematically illustratedour novel circulation system. As heretofore already mentioned, thecontrol system included in the gas impermeable barrier 10 forcontrolling the introduction, circulation and exhaustion of gases withinthe sterilizing chamber 12 is incorporated by reference in the FIG. 7embodiment as well as the FIGS. 1-5 embodiments of our invention.Moreover, it will be understood that this control system may be utilizedwith the FIG. 6 embodiment in lieu of conventional sterilizer controls.In the FIG. 1 embodiment, such control apparatus is mounted on theunderside of the tray 20 as illustrated in FIGS. 1, 3 and 4 and isspaced from the floor over which the portable unit is transported byfour conventional casters 42 mounted on the lower surface of thesupporting tray 20. Rigidly mounted on tray 20 at the left-hand endthereof as viewed in FIGS. l3 inclusive there is provided a handle 19 bywhich the operator may push the portable sterilizer to any desiredlocation.

With reference to FIGS. 1-3 inclusive, we have shown a control box orbase 44 to which the gas impermeable barrier 10 is connected. Controlbase 44 houses the electrical controls for the motor and solenoid valvesand any other control mechanism for operating the hereinafter describedcirculation system. The details of the electric circuitry will bedescribed hereinafter under the heading Electrical Circuitry whichterminates in a suitable electrical cord 45 and plug. It will beunderstood that any number of variations in such electrical circuitrycould be provided all within the spirit of the present invention and notdepart from the spirit of this invention which may be manuallycontrolled as well as automatically controlled.

The control system, as illustrated in FIGS. 1 to 4 includes an air inlethousing 46 and an air outlet housing 48. Attached to the air inlethousing 46 is a suitable inlet 49 communicating with a dust filter 50,valve 51, deodorizer 52, heater 53, and bacteria filter 55 all in seriesas shown schematically in FIG. 4. Also attached to housing 46 is asecond valve 56 communicating with an ampule containing an aromatic ormasking or odor destroying material 58 supplying the deodorizer 52.Outlet housing 48 has three compartments 60, 62 and 70. A motorized fan58 is rigidly mounted substantially in the center of the centercompartment 60 as shown in FIG. 2 with the fan blade being received in acorresponding opening provided in a horizontal partition 59. Theleft-hand compartment 62 as viewed in FIG. 4 is the sterilant disposalcompartment in which is mounted a micron-partical size filter 64. Forpreventing bacteria from contaminated mattresses (typical goods to besterilized) from being exhausted from the system into the atmosphere, agas sorbing agent 65 such as activated charcoal fills the remainder ofchamber 62. There is a check valve 66 disposed in the partition be tweenthe fan compartment 60 and sterilant disposal compartment 62. There isan outlet 67 through which purged air is exhausted. The right-handcompartment 70 has three sections, the left-hand one of which houses asecond heater 68. The right-hand compartment 70 also includes a centerhumidifier section adapted to receive water 72; a partition 71 separatesthe humidifier section from a right-hand sterilant injection sectionreceiving liquid sterilant 73 adapted to assume a gaseous state. Thereare a pair of conduits or tubes 75 and 76 having in-line valves 77 and78 respectively. Conduit or tube 75 communicates between an ampule orother source of water at 79 and the humidifier section. Likewise, theconduit 76 communicates between a pierceable ampule or other suitablesupply of sterilant 80 adapted to assume a gaseous state. For a portableconstruction such as is illustrated in FIGS. 14 inclusive, it isdesirable to mount the Water ampule 79 and sterilant ampule 80 in thecontrol base 44 so that periodically they may be conveniently replacedor replenished after lifting the lid of the control box 44.

Although not an essential element of my invention, with a portableconstruction such as this, we have found it particularly desirable toprovide a sterilant in liquid form pressurized or unpressurized in acontainer adapted to be pierced by a pin or other means well-known inthe art, to open the container thereby to provide liquid sterilantreadily adapted to assume a gaseous state. A conduit or connecting pipe82 communicates between the two housings 48 and 46 with a connectorvalve 83 in line.

We provide a selected length of perforated exhaust hose 85 shown inbroken line in FIG. 1, in solid line but broken away in FIG. 2, and onlya terminal portion thereof in solid line in FIG. 4. The multipleperforations extending throughout the entire length of the hose 85receives gaseous sterilant and/or air being withdrawn from the flexiblechamber by the fan 58, after which the air passes through a pair ofconduits 87 communicating between the perforated hose 85 and the top ofcenter fan compartment 60. Gaseous mediums pass through a dust filter 90mounted in the top of the center fan compartment 60. The hold-down plate1 8 has a pair of spaced openings adapted to receive terminal ends ofthe perforated hose 85 so that the hose 85 is removably mounted to theholddown plate 18. The perforated hose 85 as seen in FIGS. 1 and 2,extends around the mattresses 24.

As seen in FIGS. 2 and 4, clear plastic cover 93 which overlies andseals the outlet housing 48 from the sterilizing chamber provides aneasy access for repair of the fan 58 and access to the threecompartments comprising the housing 48.

The gas impermeable barrier 10A of the FIG. 5 embodiment is identical tothe FIG. 1 embodiment except that communication with the flexible bag12A is through flexible couplings 28 and 29 rigidly connectedrespectively to the two housings 46A and 48A. As described above, thereare releasable clamps or bands 26 and 27 interconnecting the bag 12Awith the hoses 28 and 29 respectively. In all illustrated embodimentsthe gas impermeable barrier 10 is sealed in gas-tight relationship withthe gas impermeable bag 12.

OPERATION For the purposes of illustration, the bag 12 is illustrated inFIGS. 1, 2 and 3 in an inflated position in order that the goods to besterilized, i.e., the mattresses 24, could be more easilydistinguishable from the bag 12. While the foregoing described structurecould operate under positive pressure, it is preferable to operate atsub-atmospheric pressure in order to guarantee no hazards of leakage inthe event of damage to the bag itself. Under sub-atmospheric conditions,the flexible bag 12 will conform to the shape of the goods to besterilized.

The mattresses 24 are placed on the bottom part 23 of bag 12 withalternate layers of spacers 25 to facilitate penetration of the goods bythe sterilant. The upper part 21 of bag 12 is then placed over themattresses and the operator zips the pressure sealing zipper 22 so thatthe bag is gas impermeable. Evacuation of the flexible chamber and goods(if permeable) is effected by closing all valves above describedairinlet valve 51, valve 56, water inlet valve 77, sterilant inlet valve 78and housing connector valve 83. These valves all being closed, the fan58 sucks air out of the flexible chamber 12 and goods (if permeable) asindicated by the arrows 95 to exhaust contaminated air from the flexiblesterilizing chamber through the dust filter 90. The air is dischargedthrough the check valve 66 and bacteria filter 64 through charcoalfilter 65 and through outlet 67 to atmosphere. It will be understoodthat the check valve opens when positive pressure is produced at theexhaust side of fan 58 to permit expulsion of air. After a preselectedevacuation period, a sub-atmospheric condition is established in theflexible chamber 12. Thereafter, the heaters 68 and 53 are turned on andvalves 77 and 83 are opened. Housing connector valve 83 when opened,releases the pressure on check valve 66 permitting it to close, therebyto maintain the sub-atmospheric pressure of approximately 15 to 25inches, water column, within the closed system and the air being drawnthrough the motorized fan compartment then passes through heater 68 tobe warmed, through the humidifying section where the Warm air ismoisturized by the water 72. Water 72 is drawn from the source 79 by thenegative pressure system; while it is preferable that the source 79 ofwater he in pressure sealed relationship with conduit 75, it will beunderstood that the fan 58 which is a conventional vacuum cleaner typefan, will maintain a sub-atmospheric pressure in the system even ifslight leaks develop in the system. The sub-atmospheric pressureguarantees that both the barrier and bag 12 are maintained asgas-impermeable, preventing leaking of sterilizing gas out of thesystem.

The warm, humidified air is circulated through the flexible bag 12 andthe goods to be sterilized in order to prop erly condition the goods forthe desired moisture conditions in accordance with the teachings of theRobert L. McDonald Patent 3,068,064. When a selected moisture conditionhas been established in the goods to be sterilized in the sterilizingchamber, valve 78 is then opened and liquid sterilant 73 from ampule 80or other source is drawn by the negative pressure into the sterilantinjection section. Preferably, the ampule 80 is sealed in gastightconnection with the conduit 76. The sterilant, preferably ethylene oxideor beta-propiolactone is adapted to readily assume a gaseous state andpass through the housing connector valve 83 and housing 46 to thechamber 12 where sterilization is effected for a selected period oftime.

The fan 58 continues to recirculate and moisturize the gaseous sterilantfrom the chamber 12 from the perforated hose 85 back through housing 48,housing connector valve 83, and housing 46 in an endless, continuouscycle until sterilization has been effected during a selectedsterilizing period. Filters 55 and 90 are sterilized with each cycle asthe sterilant is circulated through the endless cycle just described.

At the end of the sterilizing period, heaters 53 and 68 are turned offand all of the valves including 51, 56, 83, 77 and 78 are closed so thechamber is again evacuated in the same manner as heretofore described,thereby to evacuate and substantially purge the flexible chamber ofgaseous sterilant. The filter 64 sorbs the noxious and toxicsterilantand releases purged gas at outlet 67. The valve 51 is then openedthereby to draw air from outside of the chamber through the inlet 49,bacteria retentive dust filter 50, through the deodorizer 52 past theheater 53 through the sterile bacteria filter 55 into and through theflexible sterilizing bag 12 and mattresses 24, out through theperforated hose 85, conduit 87, bacteria retentive dust filter 90, pastfan 58 and out check valve 66 at 67 to atmosphere, thereby aerating thegoods and chamber with pure air for a selected aerating period. Duringthe aearation period, the valve 56, may, if desired, be opened, therebysupplying deodorant from the ampule 58 to the deodorizer 52 to deodorizethe chamber and goods during the terminal portion of the aerationperiod. Thereafter, the heater 53 and fan 58 are turned off andatmospheric pressure is established throughout the system by holdingvalve 51 open.

It will be understood from the above description that the valve 83functions to permit pressure increase or decrease at exhaust side of thefan thereby causing releasably controlled check valve 66 to open orclose respectively, thereby to releasably prevent sterilant from passingthrough the check valve 66 and outlet 67 during the sterilizing cycle,and only when valve 83 is closed will the sterilant be evacuated throughthe one-way check valve 66 and outlet 67. Valve 51 cooperates with valve83 during aeration to release the remainder of the sterilant not purgedduring evacuation.

The above sequential operation may be carried out manually orautomatically. FIG. 9 is a sequential time chart or bar graphillustrating a typical timed cycle in accordance with the sequence abovedescribed. The elongated bars in the FIG. 9 graph illustrate the.respective portions of time during which the fan and heaters areactivated and valves are open as listed according to FIG. 1 partsnumerals in vertical column A whether the cycle is manual or automatic;whereas vertical column B lists the respective periods during whichelectrical switches are closed which control the structural elementslisted in column A if the cycle is automated according to the circuit ofFIG. 8.

ELECTRICAL CIRCUITRY FIG. 8 schematically represents the electricalcontrols mounted in the control box or base 44 for automating the cycledescribed in the preceding section. In parallel across a volt AC line,is the following circuit, the switches of which are controlled by atimer motor 110 driving a shaft 112 shown in broken line in turnsequentially controlling a plurality of switches. The operator manuallycloses a switch 114 which energizes the timer motor 110 and turns on anindicator light 116.

In the sequential relationship described in the preceding section, andfor the periods of time illustrated in FIG. 9, the following switchesare sequentially closed to control elements heretofore described: switch118 is closed by the shaft 112 to energize the fan 58 which remains onduring substantially the entire cycle; after the pre-evacuation period,switch 119 is closed, thereby opening the valves 77 and 83 and turningon the heaters 53 and 68, which switch remains closed throughout thepre-humidification and during the sterilizing period; thereafter, switch120 is closed to open the sterilize valve 78 which switch remains closedthrough the selected sterilizing period; thereafter, switches 119 and120 are opened to de-energize the heaters 53 and 68 and close valves 77,78 and 83, and the post-evacuation period commences, during which periodthe fan is still running to evacuate the chambers; then switch 112closes to open valve 51 for the aeration period, and thereafter switch124 closes to open the valve 56 communicating with the deodorizer; forthe terminal portion of the cycle, switch is closed to actuate a buzzeror indicator signal 126; then switches 114, 118, 122 and 124 open tode-energize the fan 58 and close valves 51 and 56. The switch 125remains closed because the timer motor switch 114 is open so the buzzer126 continues to ring until the operator manually moves shaft 112 to theoff position.

In the alternative, preferred arrangement, the switch 122 may remainclosed to maintain valve 51 open after the fan 58 turns off, thereby toreturn the system to atmospheric pressure as suggested in the precedingsection of this disclosure, as indicated on the FIG. 9 bar-graph by theterminal broken line portion of the switch 122 bar.

While we have shown and described the preferred form of mechanism of ourinvention, it will be apparent that various modifications and changesmay be made therein particularly in the form and relation of parts,without departing from the spirit of our invention as set forth in theappended claims.

We claim:

1. A sterilizing apparatus comprising:

(a) a gas impermeable barrier; I

(b) a completely flexible and collapsible gas impermeable bag having azippered aperture permitting insertion therein of articles to besterilized and adapted to be mounted in gas-tight connection to saidbarrier;

(c) means to connect said bag to said barrier in gastight relationshiptherewith;

((1) means for introducindg into, said bag through said barrier asterilant adapted to assume a gaseous state;

(e) outlet means permitting said sterilant to pass from said bag throughsaid barrier to the external atmosphere;

(f) control means for releasably preventing sterilant from passingthrough said outlet means.

2. A sterilizing apparatus comprising:

(a) a horizontal gas impermeable barrier;

(b) a completely flexible and collapsible gas impermeable bag having azippered aperture permitting insertion therein of articles to besterilized and adapted to be mounted in gas-tight connection to saidbarrier;

() means to conect said bag to said barrier in gastight relationshiptherewith; and

(d) control means for introducing into and exhausting from said bagthrough said barrier a sterilant adapted to assume a gaseous state.

3. A sterilizer apparatus comprising:

(a) a gas impermeable barrier;

(b) a completely flexible and collapsible gas impermeable bag having azippered aperture permitting insertion therein of articles to besterilized and adapted to be mounted in gas-tight connection to saidbarrier;

(c) means to connect said bag to said barrier in gastight relationshiptherewith; and

(d) control means for reducing internal pressure of said bag tosub-atmospheric pressure, thereafter introducing sterilant adapted toassume a gaseous state into said bag and then exhausting said sterilantfrom said bag, all through said barrier.

4. A sterilizing apparatus comprising:

(a) a gas impermeable barrier;

(b) a completely flexible and collapsible gas-impermeable bag having azippered aperture permitting insertion therein of articles to besterilized and adapted to be mounted in gas-tight connection to saidbarrier;

(0) means to connect said bag to said barrier in gastight relationshiptherewith;

(d) fan means communicating with said bag through said barrier; and

(e) valve means coactive with said fan means when said valve means is ina first position for reducing internal pressure in said bag and when ina second position for circulating fluid through said bag and barrier.

5. A sterilizing apparatus comprising:

(a) a gas impermeable barrier;

(-b) a completely flexible and collapsible gas impermeable bag having azippered aperture permitting insertion therein of articles to besterilized and adapted to be mounted in gas-tight connection to saidbarrier;

(0) means to connect said bag to said barrier in gastight relationshiptherewith;

(d) fan means communicating with said bag through said barrier; and

(e) valve means coactive with said fan means when said valve means is ina first position for exhausting fluid from said bag and when in a secondposition for circulating fluid through said bag and barrier.

References Cited UNITED STATES PATENTS 2,027,042 1/1936 Hinds 21582,131,134 9/1938 Baer et al 21-58 2,965,936 12/1960 Kaye 2l58 X3,114,599 12/1963 Fanning 2198 JOSEPH SCOVRONEK, Primary Examiner US.Cl. X.R.

